Eco/Env English
2018-04-11 14:13:33
Vittorio Hernandez

Scientists from the Computer Science and Artificial Intelligence Laboratory of the Massachusetts Institute of Technology have developed a soft robot fish which they called SoFi. The robot fish can swim on its own and is lifelike in its movements so other sea animals will not be disturbed, Mashable reported.

SoFi, which is made of silicon rubber and flexible plastic, can swim, handle currents, and take photos and videos at depths of over 15 meters for up to 40 minutes at a time. The researchers based their results on test dives held in Fiji’s Rainbow Reef and were documented in the Science Robotics journal.

Researchers said that SoFi should get close to the ocean’s inhabitants without spooking them to give the world a greater insight into the lives of under-observed sea creatures. Because its housing is made from molded and 3D printed plastics, it is cheap and easy to fabricate, The Verge observed.

It has a built-in buoyancy tank full of compressed air, allowing SoFi to adjust its depth and linger at specific points in the water column. SoFi has a custom control system that uses coded audio bursts to transmit instructions from a human operator. It can swim semi-autonomously and will keep going in a specific direction without oversight, however, a handler can steer the robot left or right, up and down, by using a modified SNES controller.

Diver controls

A diver actually controls SoFi from a waterproofed Super Nintendo-like controller. The controller allows the fish to move in a straight line, turn, or dive down or up. He can also control the speed of the robot fish and allow the creature to make specific moves or turns.

SoFi is not like other autonomous underwater vehicles that are tethered to a boat or powered by a bulky propeller.  It is instead powered by a lithium polymer battery that can be found in consumer smartphones. A motor helps SoFi swim by making a side-to-side motion. The motor pushes water into two balloon-like chambers which make the robot fish bend and flex.

SoFi is also a propulsion system because it has a powerful hydraulic actuator which pumps water in and out of a pair of internal chambers as the robot moves its tail fin back and forth. The researchers noted that not only is SoFi quieter than using propellers like a submarine, it is also less dangerous because there are no sharp moving parts and has better camouflage. They added that a hydraulic tail is quieter and looks just like the real thing.

Further improvements

SoFi is scheduled for further improvements such as increasing speed by improving its pump system and modifying the design of its body and tail, Robert Katzchmann, the lead author of the study, said.

Daniela Rus, a co-author of the paper and the director of the Computer Science and Artificial Intelligence Laboratory at MIT, said the team was excited to see that SoFi could swim side by side with real fish which did not swim away. She noted it is quite different when a human diver approaches the fish. She imagines that one day, the fish might help them uncover more mysteries from the underwater world that we know so little about, The LA Times reported.

The researchers used a robot design that mimics the shape and movement of real animals. Known as biomimetics, it is an approach that created colonoscopy robots that wiggle like a worm, cockroach robots that could run alongside search-and-rescue missions, and a variety of seafaring creations that take inspiration from everything from the jellyfish to the sea turtle.

Rus said that SoFi is a finished product compared to earlier biomimetic fish. It can be an extraordinary tool for studying marine biology. She said that scientists need to collect more data to find out about the secret lives of animals that live underwater.

Rus noted that SoFi’s design can be easily scaled up or down. However, if it were bigger, it would be harder for a diver to get it into and out of the water. If it were smaller, it would struggle more against currents. She added that building a robot that can function underwater comes with unique challenges.

For instance, its electronic need must be housed in watertight compartments that are able to withstand large changes in pressure because the robot moves up and down in the water column. It also requires adjustable buoyancy so it can swim at different depths without floating off to the surface or sinking to the seafloor.

Another issue is communications because radio frequencies used to communicate with robots on land do not work in the water.

The next step could involve creating more whole schools of robots that can navigate as a single creature to collect bigger amounts of data or split off to comb the seafloor as individual scouts.

[researchpaper 리서치페이퍼=Vittorio Hernandez 기자]

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